It is proposed to continue a multidisciplinary investigation of basal-ganglia specific neuronal phosphoproteins. The program project for which renewed support is being requested consists of five parts. The first project (Principal Investigator, Dr. Angus C. Nairn) would continue the purification and characterization of phosphoprotein substrates (for cAMP dependent protein kinase) identified during the previous funding period, and develop immunological procedures to measure the state of phosphorylation of these proteins. It also proposes to carry out a detailed characterization of protein phosphatase- 1, since an understanding of the role of this phosphatase is essential to clarifying the role of DARPP-32 in the basal ganglia. The second project (Principal Investigator, Dr. Eric L. Gustafson) would continue studies involving the use of antibodies against phosphoproteins to carry out detailed immunocytochemical studies, at both the light and electron microscopic levels, of the regional, and subcellular distribution of these phosphoproteins. It proposes to study the neuroanatomical framework underlying neurotransmitter-phosphoprotein interactions in the basal ganglia. It would also study the regulation of specific phosphoprotein mRNAs in the basal ganglia, and examine these mRNAs during development. The third project (Principal Investigator, Dr. Paul Greengard) would involve a comprehensive analysis of the pharmacological and physiological regulation of the levels and phosphorylation states of the basal ganglia-enriched phosphoproteins in intact animals and brain slices. It also proposes to introduce electrophysiological techniques to study the physiological roles of protein phosphorylation in the basal ganglia by directly injecting purified phosphoproteins in their phospho and dephospho forms, protein kinases and protein phosphatases into neuronal cells and studying their effects on neuronal activity. The fourth project (Principal Investigator, Dr. Michelle E. Ehrlich) would use recombinant DNA technology to study the expression of the basal ganglia-enriched phosphoproteins, to characterize the human cDNAs for these proteins for use in human molecular genetics studies, and to establish transgenic mice to better understand the function of these proteins in vivo. The fifth project (Principal Investigator, Dr. Kang Tsou) would provide a core facility. Primary tissue cultures of neuronal and glial cells will be grown and maintained for the study of the factors that regulate the expression and phosphorylation state of basal ganglia-specific phosphoproteins. The core facility would also isolate and maintain continuous supplies of monoclonal antibodies against the basal ganglia specific phosphoproteins for the various components of the program project. It is believed that this multidisciplinary approach will provide vital information about the molecular nature of signal transduction in the nervous system as well as provide possible important clues toward the understanding of the etiology of a variety of neuropsychiatric disorders including schizophrenia.